An official website of the United States government
Abstract BackgroundUndergraduate students consistently struggle with mastering concepts related to thermodynamics. Prior work has shown that haptic technology and intensive hands‐on workshops help improve learning outcomes relative to traditional lecture‐based thermodynamics instruction. The current study takes a more feasible approach to improving thermal understanding by incorporating simple mechanical objects into individual problem‐solving exercises. Purpose/HypothesesThis study tests the impact of simple mechanical objects on learning outcomes (specifically, problem‐solving performance and conceptual understanding) for third‐year undergraduate engineering students in a thermodynamics course across a semester. Design/MethodDuring the semester, 119 engineering students in two sections of an undergraduate thermodynamics course completed three 15‐min, self‐guided problem‐solving tasks, one section without and the other with a simple and relevant physical object. Performance on the tasks and improvements in thermodynamics comprehension (measured via Thermal and Transport Concept Inventory scores) were compared between the two sections. ResultsStudents who had a simple, relevant object available to solve three thermodynamics problems consistently outperformed their counterparts without objects, although only to statistical significance when examining the simple effects for the third problem. At the end of the semester, students who had completed the tasks with the objects displayed significantly greater improvements in thermodynamics comprehension than their peers without the relevant object. Higher mechanical aptitude facilitated the beneficial effect of object availability on comprehension improvements. ConclusionFindings suggest that the incorporation of simple mechanical objects into active learning exercises in thermodynamics curricula could facilitate student learning in thermodynamics and potentially other abstract domains.
more »
« less
The Brinkman-Fourier system with ideal gas equilibrium
In this work, we will introduce a general framework to derive the thermodynamics of a fluid mechanical system, which guarantees the consistence between the energetic variational approaches with the laws of thermodynamics. In particular, we will focus on the coupling between the thermal and mechanical forces. We follow the framework for a classical gas with ideal gas equilibrium and present the existences of weak solutions to this thermodynamic system coupled with the Brinkman-type equation to govern the velocity field.
more »
« less
- PAR ID:
- 10313195
- Date Published:
- Journal Name:
- Discrete & Continuous Dynamical Systems
- Volume:
- 42
- Issue:
- 1
- ISSN:
- 1078-0947
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
The application of the Young–Laplace equation to a solid–liquid interface is considered. Computer simulations show that the pressure inside a solid cluster of hard spheres is smaller than the external pressure of the liquid (both for small and large clusters). This would suggest a negative value for the interfacial free energy. We show that in a Gibbsian description of the thermodynamics of a curved solid–liquid interface in equilibrium, the choice of the thermodynamic (rather than mechanical) pressure is required, as suggested by Tolman for the liquid–gas scenario. With this definition, the interfacial free energy is positive, and the values obtained are in excellent agreement with previous results from nucleation studies. Although, for a curved fluid–fluid interface, there is no distinction between mechanical and thermal pressures (for a sufficiently large inner phase), in the solid–liquid interface, they do not coincide, as hypothesized by Gibbs.more » « less
-
Abstract Jamming is the transition from a fluid‐like state to a solid‐like state of a packing system. Recent studies have shown that jamming transition depends upon many factors: particle shape, friction/cohesion between particles, particle size dispersity, the stress of the packing, etc. This study aims to contribute to this growing area of research by exploring the jamming density of soil with strong dispersity. In analogous to Gibbs excess energy, we introduce excess volume‐potentials for each species. We then proposed a mathematical model to quantitatively compute the jamming density based on the second law of equilibrium in thermodynamics. This approach is validated using experimental results on glass beads and on silty sand. It is hoped that this study will provide to a deeper understanding of the link between jamming density, packing dispersity and the second law of thermodynamics.more » « less
-
Low temperature plasmas are open driven thermodynamic systems capable of increasing the free energy of the mass that flows through them. An interesting thing about low temperature plasmas is that different species have different temperatures at the same location in space. Since thermal equilibrium cannot be assumed, many of the familiar results of equilibrium thermodynamics cannot be applied in their familiar form to predict, e.g., the direction of a chemical reaction. From the perspective of classical processing governed by thermal equilibrium, examples of highly unexpected gas-phase chemical reactions (CO2 dissociation, NO, N2H4, O3 synthesis) and solid material transformations (surface activation, size-focusing, and hyperdoping) promoted by low temperature plasmas are presented. The lack of a known chemical reaction equilibrium criterion prevents assessment of predictive kinetics models of low temperature plasmas, to ensure that they comply with the laws of thermodynamics. There is a need for a general method to predict chemical reaction equilibrium in low temperature plasmas or an alternative method to establish the thermodynamic admissibility of a proposed kinetics model. Toward those ends, two ideas are explored in this work. The first idea is that chemical reactions in low temperature plasmas proceed toward a thermal equilibrium state at an effective temperature intermediate between the neutral gas temperature and the electron temperature. The effective temperature hypothesis is simple, and surprisingly is adequate for elucidation in some systems, but it lacks generality. The general equation for nonequilibrium reversible–irreversible coupling (GENERIC) is a general beyond equilibrium thermodynamics framework that can be used to rigorously establish the thermodynamic admissibility of a set of dynamic modeling equations, such as a kinetic model, without knowledge of the final state that the system is tending toward. The use of GENERIC is described by way of example using a two-temperature hydrodynamic model from the literature. The conclusion of the GENERIC analysis presented in this work is that the concept of superlocal equilibrium is thermodynamically admissible and may be applied to describe low temperature plasmas, provided that appropriate terms are included for exchange of internal energy and momentum between different species that may have different temperatures and bulk velocities at the same location in space. The concept of superlocal equilibrium is expected to be of utility in future work focused on deriving equilibrium criteria for low temperature plasmas.more » « less
-
We present a thermodynamically consistent energetic variational model for active nematics driven by ATP hydrolysis. Extending the classical Toner–Tu framework, we introduce a chemo-mechanical coupling mechanism in which the self-advection and polarization dynamics are modulated by the ATP hydrolysis rate. The model is derived using an energetic variational approach that integrates both chemical free energy and mechanical energy into a unified energy dissipation law. The reaction rate equation explicitly incorporates mechanical feedback, revealing how active transport and alignment interactions influence chemical fluxes and vice versa. This formulation not only preserves consistency with non-equilibrium thermodynamics but also provides a transparent pathway for modeling energy transduction in active systems. We also present numerical simulations demonstrating the positive energy transduction under a specific choice of model parameters. The new modeling framework offers new insights into energy transduction and regulation mechanisms in biologically related active systems.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3934/dcds.2021123
